Glass for autonomous car

ABSTRACT

A trim element for a motor vehicle that includes at least one glass sheet having an absorption coefficient lower than 5 m−1 in the wavelength range from 1051 nm to 1650 nm and having an external and an internal faces. An infrared-based remote sensing device in the wavelength range from 1051 nm to 1650 nm is placed behind the internal face of the glass sheet.

This application is a Continuation of U.S. Ser. No. 16/497,074, filedSep. 24, 2019, pending, which is a 371 Application of PCT/EP2018/058176,filed Mar. 29, 2018 and claims benefit of EP Application No. 17163902.4,filed Mar. 30, 2017. The contents of each of these applications areincorporated herein by reference in their entirety.

The invention concerns a glass comprising an infrared-based remotesensing device and particularly a LiDAR sensors. More particularly, theinvention concerns a glass trim element comprising new generation LiDARsensors to be integrated in an autonomous car.

Glass trim for automotive refers to the items that can be added to theinterior or exterior of an automobile to increase its appeal or to masksome unaesthetic parts of the automotive. There are several types of cartrim. Some are used to protect some part of the interior or exteriorvehicle from unwanted damage that can be caused by the passenger, whileothers are simply for aesthetics.

The most popular trim element are chrome or plastic trim. Automotivetrim element may be made of vinyl, artificial leather, wood grain andleather or more generally made of plastics, polycarbonate elements. Thissolution is often aesthetic but does not allow adding directly somefunctions on the trim as such “touch screen functionalities” . . . .

However, today, more and more glass trim elements are considered inautomotive field. For example such as glass trim elements are used ascar trunk cover, cover for A-, B-, C-, D- pillars (vertical or nearvertical supports of a car's window area—designated respectively as theA, B, C or (in larger cars) D-pillar, moving from the front to rear, inprofile view) or interior trim element on the dashboard, console, doortrim . . . . Such as glass trim elements are described in patentapplications EP 15 177 303.3, EP 15 177 243.1 and EP 16 160 906.0 whichare integrated in the present description by reference.

The use of glass trim element in automotive field thus offers theopportunity to add some functionalities as touch functionalities whichare no permitted with plastics or others classically used material.

Also, today the trend is to use more and more autonomous car to becompletely used in the future. For example, futuristic autonomous car,also called driver lower car, self-driving car, robotic car, is avehicle that is capable of sensing its environment and navigatingwithout human input.

Autonomous vehicles detect surroundings using radar, LiDAR (acronym ofLight Detection And Ranging), GPS, Odometry, and computer vision.Advanced control systems interpret sensory information to identifyappropriate navigation paths, as well as obstacles and relevant signage.Autonomous cars have control systems that are capable of analyzingsensory data to distinguish between different cars on the road, which isvery useful in planning a path to the desired destination.

Today, autonomous cars comprise “mushrooms-like” LiDAR sensors poppingup all along the car metal body. Those “mushrooms” are for exampleplaced on the roof or on car external rear view mirrors. In addition tobeing unaesthetic, they are imposing and take up much space which is notin line with the expectation of car designers preparing future cardesign with very smooth and curvy line which are incompatible withoutside sensors. LiDAR sensors may be also embedded into the bumpers orheadlight systems which implies other drawbacks such a higher exposureto damage and external climatic conditions.

Thus, there is a need for an alternative to the use of imposing andunaesthetic LiDAR sensors such as “mushrooms” for autonomous cars orLiDAR on bumper.

According to the present invention, the infrared-based remote sensingdevice LiDAR sensors are new generation LIDAR based on scanning,rotating, flashing or solid state LiDARs and enabling 3D mapping thesurroundings around the vehicle. Thus, the IR based sensor allows tomake precise mapping of the surrounding of the vehicle which is used todrive correctly the autonomous car and to prevent any shock with anobstacle.

LiDAR (also written Lidar, LIDAR or LADAR) is a technology that measuresdistance by illuminating a target with a laser light. They areparticularly scanning, rotating, flashing or solid state LiDAR. Thescanning or rotating LiDARS are using moving-lasers beams while flashingand solid state LiDAR emits light pulses which reflect off objects

Thus, there is a need today for infrared (IR) based remote sensingdevice/sensor capable of object detection and 3D mapping thesurroundings around the vehicle such as LiDAR installed in theautonomous car and particularly completely integrated to the car.

Thus, solutions from prior art can not reply to requirement for LiDARnew generation particularly because glass with integrated LiDAR was notconsidered as a possible solution.

Currently, there is no solution which allows IR signal to go througheither the car body or glass parts such as windshield or backlite of acar with enough intensity.

Thus, the present invention proposes a solution wherein a LiDAR newgeneration sensor may integrated in the autonomous car combing highdetection range, minimal design change and higher safety.

This solution is possible by dint of integration of a LiDAR sensor on anautomotive glass trim element that exhibits a sufficient IR transmissionfor the sensor to operate properly. According to the present invention,the glass trim element is different than a vision glass such aswindshield, sidelite . . . . Thus the specifications and needs for aglass trim element are different than those for a vision glazing.

For simplicity, the numbering of the glass sheets in the followingdescription refers to the numbering nomenclature conventionally used forglazing. Thus, the face of the glazing in contact with the environmentoutside the vehicle is known as the side 1 and the surface in contactwith the internal medium, that is to say the passenger compartment, iscalled face 2. For a laminated glazing, the glass sheet in contact withthe outside environment the vehicle is known as the side 1 and thesurface in contact with the internal part, namely the passengercompartment, is called face 4.

For avoidance of doubt, the terms “external” and “internal” refer to theorientation of the glass trim element during installation in a vehicle.

Also for avoidance of doubt, the present invention is applicable for allmeans of transport such as automotive, train, plane . . . but also othervehicles like drones, . . .

Thus, the present invention concerns a glass trim element for a motorvehicle comprising at least one glass sheet having an absorptioncoefficient lower than 5 m⁻¹ in the wavelength range from 1051 nm to1650 nm and having an external and an internal faces.

According to this present invention, an infrared-based remote sensingdevice operating in the wavelength range from 1051 nm to 1650 nm isplaced behind the internal face of the glass sheet.

According to a preferred embodiment of the present invention, the glasstrim element comprises an infrared-based remote sensing device in thewavelength range from 1051 nm to 1650 nm placed behind the internal faceof the glass sheet.

According to the invention, the glass sheet has an absorptioncoefficient lower than 5 m⁻¹ in the wavelength range from 1051 nm to1650 nm. To quantify the low absorption of the glass sheet in theinfrared range, in the present description, the absorption coefficientis used in the wavelength range from 1051 mu to 1650 nm. The absorptioncoefficient is defined by the ratio between the absorbance and theoptical path length traversed by electromagnetic radiation in a givenenvironment. It is expressed in m⁻¹. It is therefore independent of thethickness of the material but it is function of the wavelength of theabsorbed radiation and the chemical nature of the material.

In the case of glass, the absorption coefficient (μ) at a chosenwavelength λ can be calculated from a measurement in transmission (T) aswell as the refractive index n of the material (thick=thickness), thevalues of n, ρ and T being a function of the chosen wavelength λ:

$\mu = {{- \frac{1}{thick}} \cdot {\ln\left\lbrack \frac{{- \left( {1 - \rho} \right)^{2}} + \sqrt{\left( {1 - \rho} \right)^{2} + {4 \cdot T^{2} \cdot \rho^{2}}}}{2 \cdot T \cdot \rho^{2}} \right\rbrack}}$with  ρ = (n − 1)²/(n + 1)².

The glass sheet according to the invention preferably has an absorptioncoefficient in the wavelength range of 1051 nm to 1650 nm, generallyused in optical technologies relating to the invention, very lowcompared to conventional glasses. In particular, the glass sheetaccording to the invention has an absorption coefficient in thewavelength range from 1051 nm to 1650 nm lower than 5 m⁻¹.

Preferably, the glass sheet has an absorption coefficient of lower than3 m⁻¹, or even lower than 2 m⁻¹ and, even more preferably lower than 1m⁻¹, or even lower than 0.8 m⁻¹.

A low absorption presents an additional advantage that the final IRtransmission is less impacted by the optical path in the material. Itmeans that for large field of view (FOV) sensors with high apertureangles the intensity perceived at the various angles (in different areasare the image) will be more uniform, especially when the sensor isoptically coupled to the glazing.

Thus, when an autonomous vehicle encounters an unexpected drivingenvironment unsuitable for autonomous operation, such as roadconstruction or an obstruction, vehicle sensors through the glazingaccording to the invention can capture data about the vehicle and theunexpected driving environment. The captured data can be sent to aremote operator or to the central intelligence unit. The remote operatoror unit can operate the vehicle or issue commands to the autonomousvehicle to be executed on various vehicle systems. The captured datasent to the remote operator/unit can be optimized to conserve bandwidth,such as by sending a limited subset of the captured data.

According to one preferred embodiment of the present invention, theglass trim element is an exterior glass trim element. More particularly,the exterior glass trim element is a glass trim element for A, B- andC-pillar or trunk cover of a vehicle.

According to another embodiment of the present invention, the exteriorglass trim element may be a glass trim element disposed in the side andmore particularly on the edge of on door of the vehicle.

Thus, the LiDAR may capture images and data from each sides of thevehicle.

More preferably, the autonomous car is provided with exterior glass trimaccording to the present invention and a glazing such as windshield,sidelites, backlites with also integrated LiDAR in order to cover allsides of the car and to map all around the car.

According to one embodiment of the present invention, the glass trimelement according to the present invention may be also used to coverLiDAR which are integrated into car's bumper. Thus, the LiDAR isprotected without reducing the LiDAR functionalities, performances.

According to the invention, the glass sheet is made of glass which maybelong to different categories with the particularity of having anabsorption coefficient lower than 5 m⁻¹ in the wavelength range from1051 nm to 1650 nm. The glass can thus be a soda-lime-silica type glass,alumino-silicate, boro-silicate,

Preferably, the glass sheet having a high level of near infraredradiation transmission is an extra-clear glass.

Preferably, the base glass composition of the invention comprises atotal content expressed in weight percentages of glass:

SiO₂ 55-85% Al₂O₃  0-30% B₂O₃  0-20% Na₂O  0-25% CaO  0-20% MgO  0-15%K₂O  0-20% BaO  0-20%

More preferably, the base glass composition comprises according to theinvention in a content, expressed as total weight of glass percentages:

SiO₂ 55-78% Al₂O₃  0-18% B₂O₃  0-18% Na₂O  0-20% CaO  0-15% MgO  0-10%K₂O  0-10% BaO  0-5%

More preferably, for reasons of lower production costs, the at least oneglass sheet according to the invention is made of soda-lime glass.Advantageously, according to this embodiment, the base glass compositioncomprises a content, expressed as the total weight of glass percentages:

SiO₂ 60-75% Al₂O₃  0-6% B₂O₃  0-4% CaO  0-15% MgO  0-10% Na₂O  5-20% K₂O 0-10% BaO  0-5%.

In addition to its basic composition, the glass may include othercomponents, nature and adapted according to quantity of the desiredeffect.

A solution proposed in the invention to obtain a very transparent glassin the high infrared (IR), with weak or no impact on its aesthetic orits color, is to combine in the glass composition a low iron quantityand chromium in a range of specific contents.

Thus, according to a first embodiment, the glass sheet preferably has acomposition which comprises a content, expressed as the total weight ofglass percentages:

Fe total (expressed asFe₂O₃)  0.002-0.06% Cr₂O₃ 0.0001-0.06%.

Such glass compositions combining low levels of iron and chromium showedparticularly good performance in terms of infrared reflection and show ahigh transparency in the visible and a little marked tint, near a glasscalled “extra-clear”. These compositions are described in internationalapplications WO2014128016A1, WO2014180679A1, WO2015011040A1,WO2015011041A1, WO2015011042A1, WO2015011043A1 and WO2015011044A1,incorporated by reference in the present application. According to thisfirst particular embodiment, the composition preferably comprises achromium content (expressed as Cr2O3) from 0.002 to 0.06% by weightrelative to the total weight of the glass. Such contents of chromium itpossible to further improve the infrared reflection.

According to a second embodiment, the glass sheet has a compositionwhich comprises a content, expressed as the total weight of glasspercentages:

Fe total (expressed as Fe₂O₃)  0.002-0.06% Cr₂O₃ 0.0015-1% Co 0.0001-1%.

Such chromium and cobalt based glass compositions showed particularlygood performance in terms of infrared reflection while offeringinteresting possibilities in terms of aesthetics/color (bluishneutrality to intense coloration even up opacity). Such compositions aredescribed in European patent application No. 13 198 454.4, incorporatedby reference herein.

According to a third embodiment, the glass sheets have a compositionwhich comprises a content, expressed as the total weight of glasspercentages:

total iron (expressed as Fe₂O₃)  0.02-1% Cr₂O₃  0.002-0.5% Co0.0001-0.5%.

Preferably, according to this embodiment, the composition comprises:0.06%<Total Iron≤1%.

Such compositions based on chromium and cobalt are used to obtaincolored glass sheets in the blue-green range, comparable in terms ofcolor and light transmission with blue and green glasses on the market,but with performances particularly good in terms of infrared reflection.Such compositions are described in European patent applicationEP15172780.7, and incorporated by reference into the presentapplication.

According to a fourth embodiment, the glass sheet has a compositionwhich comprises a content, expressed as the total weight of glasspercentages:

total iron (expressed as Fe₂O₃)  0.002-1% Cr₂O₃  0.001-0.5% Co0.0001-0.5%. Se 0.0003-0.5%.

Such glass compositions based on chromium, cobalt and selenium haveshown particularly good performance in terms of infrared reflection,while offering interesting possibilities in terms of aesthetics/color(gray neutral to slight staining intense in the gray-bronze range). Suchcompositions are described in the application of European patentEP15172779.9, and incorporated by reference into the presentapplication.

According to a first alternative embodiment, the glass sheet has acomposition which comprises a content, expressed as the total weight ofglass percentages:

total iron (expressed as Fe₂O₃) 0.002-0.06% CeO₂ 0.001-1%.

Such compositions are described in European patent application No. 13193 345.9, incorporated by reference herein.

According to another alternative embodiment, the glass has a compositionwhich comprises a content. expressed as the total weight of glasspercentages:

total iron (expressed as Fe₂O₃) 0.002-0.06%;

and one of the following components:

-   -   manganese (calculated as MnO) in an amount ranging from 0.01 to        1% by weight;    -   antimony (expressed as Sb₇O₃), in an amount ranging from 0.01 to        1% by weight;    -   arsenic (expressed as As₂O₃), in an amount ranging from 0.01 to        1% by weight, or    -   copper (expressed as CuO), in an amount ranging from 0.0002 to        0.1% by weight.

Such compositions are described in European patent application No. 14167 942.3, incorporated by reference herein.

According to the present invention, the glass sheet may be totally orpartially curved to correctly fit with the particular design of thevehicle.

The glass sheet according to the invention may advantageously bechemically or thermally tempered in order to enhance the resistivity ofthe cover part of the exterior trim element.

The glass sheet according to the invention can have a thickness varyingbetween 0.1 and 5 mm. Advantageously, the glass sheet according to theinvention may have a thickness varying between 0.1 and 3 mm. Preferably,for reasons of weight, the thickness of the glass sheet according to theinvention is from 0.1 to 2.2 mm.

According to another embodiment of the invention, the at least one trimelement is made of heat treated glass sheet, for example annealed ortempered and/or bended glass sheet. Typically, this involves heating theglass sheet (coated or not) in a furnace to a temperature of at least580° C., more preferably of at least about 600° C. and still morepreferably of at least 620° C. before rapidly cooling down the glasssubstrate. This tempering and/or bending can take place for a period ofat least 4 minutes, at least 5 minutes, or more in different situations.

According to one embodiment of the present invention, the glass sheetmay comprise means to selectively filtering the infrared from sunradiation.

According to a preferred embodiment of the invention, the glass trimelement is a laminated glass trim element comprising an exterior and aninterior glass sheets laminated with at least one thermoplasticinterlayer and wherein the exterior and an interior glass sheets arehigh level of near infrared radiation transmission glass sheets havingan absorption coefficient lower than 5 m⁻¹ in the wavelength range from1051 nm to 1650 nm.

According to the present invention, a LiDAR instrument is anoptoelectronic system composed of at least a laser transmitter, at leasta receiver comprising a light collector (telescope or other optics) andat least a photodetector which converts the light into an electricalsignal and an electronic processing chain signal that extracts theinformation sought.

The LiDAR is placed on the internal face of the glass trim element(namely face 2) in case of one glass sheet trim element.

Preferably, the LiDAR is placed in a place where the LiDAR has the bestangle to cover the biggest surface.

According to another embodiment of the present invention, the glass trimelement is a laminated glass trim element wherein the LiDAR is placed onthe internal face of the inner glass sheet namely the face 4.

Advantageously, the IR-based remote sensing device is optically coupledto the internal face of the glass trim element. For example, a softmaterial that fits refractive index of the glass trim element and theexternal lens of the LiDAR may be used.

According to another advantageous embodiment of the invention, the glasssheet is coated with at least one antireflection layer. Anantireflection layer according to the invention may, for example, be alayer based on porous silica having a low refractive index or it may becomposed of several layers (stack), in particular a stack of layers ofdielectric material alternating layers having low and high refractiveindexes and terminating in a layer having a low refractive index. Suchcoating may be provided on face(s) 1 or/and 2 for a single glass trimelement or on face(s) 1 or/and 4 for a laminated glass trim element. Atextured glass sheet may be also used. Etching or coating techniques mayas well be used in order to avoid reflection.

According to a preferred embodiment, the automotive equipped with aglass trim element according the present invention also comprises aglazing (windshield, sidelite, backlite . . . ) comprising an IR-basedremote sensing device in order to precise mapping of the surrounding ofthe car which is used to drive correctly the autonomous car and toprevent any shock with an obstacle.

According to one embodiment of the present invention, the glass sheethas a value of light transmission lower than the value of infraredtransmission. Particularly, according to another embodiment of thepresent invention, the value of light transmission in the visible rangeis lower than 10% and the value of near infrared transmission is higherthan 50%.

According to another advantageous embodiment of the invention, the glasssheet is covered with at least one IR transparent absorbing (tinted)and/or reflecting coating in order to hide the un-aesthetic element ofthe sensor from the outside while ensuring a good level of operatingperformances. This coating may, for example, be composed of at least onelayer of black ink having no (or very low) transmission in the visibleoptical range but having a high transparency in the infrared range ofinterest for the application. Such ink can be made of organic compoundsas, for example, commercial products manufactured by Seiko Advance Ltd.Or Teikoku Printing Ink Mfg. Co. Ltd. that can achieve transmission <5%in the 400-750 nm range and >70% in the 850-1650 nm range. The coatingmay be provided on face(s) 1 or/and 2 for a single glass trim element oron face(s) 1 or/and 4 for a laminated automotive glazing, depending ofits durability.

According to another embodiment of the invention, the glass sheet may becovered with a multilayer coating optimized to reflect selectively thevisible range while maintaining high IR transmission. Some propertiessuch as observed on Kromatix® product are thus sought. These propertiesensure a total low IR absorbance of the complete system when such layeris deposited on adequate glass composition. The coating may be providedon face(s) 1 or/and 2 for a single automotive glazing element or onface(s) 1 or/and 4 for a laminated glass trim element, depending of itsdurability.

1. A trim element for a motor vehicle comprising at least one glasssheet having an absorption coefficient lower than 5 m⁻¹ in thewavelength range from 1051 nm to 1650 nm and having an external face andan internal face, wherein an infrared-based remote sensing device in thewavelength range from 1051 nm to 1650 nm is placed behind the internalface of the glass sheet, wherein the trim element is not part of anautomotive windshield, sidelite, or backlite.
 2. The trim elementaccording to claim 1, wherein the trim element is an exterior glass trimelement.
 3. The trim element according to claim 1, wherein theabsorption coefficient of the at least one glass sheet is lower than 1m⁻¹.
 4. The trim element according to claim 1, wherein theinfrared-based remote sensing device is optically coupled to theinternal face of the glazing.
 5. The trim element according to claim 1,wherein the trim element is a laminated trim element comprising anexterior glass sheet and an interior glass sheet laminated with at leastone thermoplastic interlayer and wherein the exterior and interior glasssheets have an absorption coefficient lower than 5 m⁻¹ in the wavelengthrange from 1051 nm to 1650 nm and wherein the infrared-based remotesensing device is placed on the internal face of the internal glasssheet.
 6. The trim element according to claim 1, wherein the at leastone glass sheet comprises a content, expressed as the total weight ofglass percentages: total iron (expressed as Fe₂O₃) 0.002 to 0.06%; Cr₂O₃0.0001 to 0.06%.
 7. The trim element according to claim 1, wherein theat least the one glass sheet comprises a content, expressed as the totalweight of glass percentages: total iron (expressed as Fe₂O₃) 0.002 to0.06%; Cr₂O₃ 0.0015 to 1%; and Co 0.0001 to 1%.
 8. The trim elementaccording to claim 1, wherein the at least one glass sheet comprises acontent, expressed as the total weight of glass percentages: total iron(expressed as Fe₂O₃) 0.02 to 1%; Cr₂O₃ 0.002 to 0.5%; and Co 0.0001 to0.5%.
 9. The trim element according to claim 1, wherein the at least oneglass sheet comprises a content, expressed as the total weight of glasspercentages: total iron (expressed as Fe₂O₃) from 0.002 to 1%; Cr₂O₃0.001 to 0.5%; Co 0.0001 to 0.5%; and Se 0.0003 to 0.5%.
 10. The trimelement according to claim 1, wherein the at least one glass is anextra-clear glass.
 11. The trim element according to claim 1, whereinthe infrared-based remote sensing device is a LIDAR system based onscanning, rotating, flashing or solid state LiDARs and enabling of 3Dmapping the surroundings around the vehicle.
 12. The trim elementaccording to claim 1, wherein an anti-reflective coating is provided onthe surface of the automotive glazing.
 13. The trim element according toclaim 1, wherein at least one glass sheet is covered with at least onenear-infrared transparent coating that absorbs and/or reflects thevisible light.
 14. The trim element according to claim 1, wherein thetrim element is a cover for A-, B- and C-pillar or a cover for trunk ofa motor vehicle.
 15. The trim element according to claim 1, wherein avalue of light transmission of the glass sheet is lower than a value ofnear infrared transmission.
 16. The trim element according to claim 5,wherein the exterior and interior glass sheets have a visible lighttransmission value lower than 10% and a near infrared transmission valuehigher than 50%.